mutations are selected against if they have a positive effect on an individual later on in life. For instance if a beneficial or deleterious mutation occurs only after an individual's reproductive phase, then it will not affect fitness, which therefore can not be selected against. Subsequently, these later mutations and effects are considered to be in the "shadow region" of selection." Natural selection Group selection Group selection is based on the idea that all members of a given group will either succeed or fail together depending on the circumstance. With this mechanism, genetic drift occurs collectively to all in the group and sets them apart from other groups of its own species. This is different than individual selection, as it focuses on the group rather than the individual. Often also postreproductive individuals make intergenerational transfers: bottlenose dolphins and pilot whales guard their grandchildren; there is cooperative breeding in some mammals, many insects and about 200 species of birds; sex differences in the survival of anthropoid primates tend to correlate with the care to offspring; or an Efe infant is often attended by more than 10 people. Lee developed a formal theory integrating selection due to transfers (at all ages) with selection due to fertility. Evolvability Evolvability is the concept that a species should profit from faster genetic adaptation to its present environment. In the following examples, this is used to argue that eliminating old individuals might benefit the species overall. Skulachev (1997) has suggested that programmed ageing assists the evolution process by providing a gradually increasing challenge or obstacle to survival and reproduction, and therefore enhancing the selection of beneficial characteristics. Goldsmith (2008) proposed that though increasing the generation rate and evolution rate is beneficial for a species, it is also important to limit lifespan so older individuals will not dominate the gene pool. Yang (2013)'s model is also based on the idea that ageing accelerates the accumulation of novel adaptive genes in local populations. However, Yang changed the terminology of "evolvability" into "genetic creativity" throughout his paper to facilitate the understanding of how ageing can have a shorter-term benefit than the word "evolvability" would imply. Lenart and Vašku (2016) have also invoked evolvability as the main mechanism driving evolution of ageing. However, they proposed that even though the actual rate of aging can be an adaptation the aging itself is inevitable. In other words, evolution can change the speed